ASTM D2711 standard test method for demulsibility characteristics of lubricating oils
8. Procedure A for Oils That Do Not Contain EP Additives
8.1 Heat the bath liquid to 82 more or less 1°C (180 more or less 2°F) and maintain this temperature throughout the test.
8.2 Measure the oil under test, at room temperature, directly into the separatory funnel to a volume of 405 more or less 5 mL. Place the separatory funnel and oil in the constant-temperature bath and bring it to a temperature of 82°C (180°F). Add 45 more or less 0.5 mL of distilled water, measured at room temperature, to the oil. Immerse the stirrer in the oil and position it carefully as follows: lower the stirrer until it touches the bottom of the funnel, then raise it approximately 25 mm (1 in.). Ensure that the vertical axis of the stirrer corresponds with the vertical center line of the funnel. Slowly bring the stirrer motor to a speed of 4500 more or less 500 rpm within 25 to 30 s, and operate for a total of 5 min, including the start-up time. Then withdraw the stirrer from the oil-water mixture but not entirely out of the separatory funnel. Allow the stirrer to drain for 5 min, then remove from the separatory funnel and clean.
8.3 Five hours after stirring has stopped, withdraw a 50-mL sample from the center of the funnel and approximately 50 mm (2 in.) below the surface of the oil-water mixture, using a 50-mL pipet. Discharge the contents of the pipet into a centrifuge tube and determine the water present in the sample using Test Method D 1796. Record the results as "percent water in the oil".
8.4 With minimum delay, after sampling for the "percentage of water in the oil", remove the separatory funnel from the bath and draw off any free water that has separated from the oil-water mixture into a 50-mL graduated cylinder. Allow this water to reach room temperature, measure, and record the volume.
8.5 After removing the free water from the separatory funnel, reduce the volume of the fluid remaining to 100 mL by carefully siphoning the fluid off the top (end of siphon should not be more than 20 mm below the surface of the fluid at any time) down to the 100-mL graduation mark on the separatory funnel. Drain the remaining 100 mL of fluid (oil, water, and emulsion) directly into a centrifuge tube.
8.6 Centrifuge the tube and its contents for a period of 10 to 15 min at a relative centrifugal force of 700. Record the volume of water and emulsion separated by centrifuging.
8.7 Perform a minimum of two determinations on each oil sample by repeating procedure 8.1-8.6. If the difference in the two sets of results obtained is outside the repeatability limits of Procedure A, discard them and obtain two additional sets of results.
9. Procedure B for Oils That Contain EP Additives
9.1 Heat the bath liquid to 82 more or less 1 °C (180 more or less 2 °F) and maintain this temperature throughout the test.
9.2 Measure the oil under test, at room temperature, directly into the separatory funnel to a volume of 360 more or less 5 mL. Place the separatory funnel and oil in a constant-temperature bath and bring to a temperature of 82 °C (180 °F). Add 90 more or less 0.5 mL of distilled water, measured at room temperature, to the oil. Immerse the stirrer in the oil and position it carefully as follows: lower the stirrer until it touches the bottom of the funnel, then raise it approximately 25 mm (1 in.). Ensure that the vertical axis of the stirrer corresponds with the vertical center line of the funnel. Slowly bring the stirrer motor to a speed of 2500 more or less 250 rpm within 25 to 30 s, and operate for a total of 5 min, including the start-up time (Note 2). Then withdraw the stirrer from the oil-water mixture but not entirely out of the separatory funnel. Allow the stirrer to drain for 5 min, then remove it from the separatory funnel and clean.
9.3 Five hours after stirring has stopped, withdraw a 50-mL sample from the center of the funnel approximately 50 mm (2 in.) below the surface of the oil-water mixture, using a 50-mL pipete. Discharge the contents of the pipet into a centrifuge tube and determine the water present in the sample using Test Method D1796. Record the results as "percent water in the oil".
9.4 Immediately after sampling for the "percentage of water in the oil", remove the separatory funnel from the bath and draw off any free water that has separated from the oil-water mixture into a 100-mL graduated cylinder. Allow this water to reach room temperature, measure, and record the volume.
9.5 After removing the free water from the separatory funnel, reduce the volume of the fluid remaining to 100 mL by carefully siphoning the fluid off the top (end of siphon should not be more than 20 mm below the surface of the fluid at any time) down to the 100-mL graduation mark on the separatory funnel. Drain the remaining 100 mL of fluid (oil, water and emulsion) directly into a centrifuge tube.
9.6 Centrifuge the tube and its contents for a period of 10 to 15 min at a relative centrifugal force of 700. Record the volume of water and emulsion separated by centrifuging.
9.7 Perform a minimum of two determinations on each oil sample by repeating procedure 9.1-9.3. If the difference in the two sets of results obtained is outside the repeatability limits of Procedure B, discard them and obtain two additional sets of results.
NOTE 2 - The stirring motor may slow down when testing high-viscosity or emuslion-forming oils. Check speed frequently during the 5-min stirring period and adjust as necessary.
